Capistrano SSH agent forwarding for shared hosts where authentication fails when accessing repos (not complete config.rb)

config.rb

default_run_options[:pty] = true  # Must be set for the password prompt from git to work

# Tell Capistrano to use agent forwarding with this command. uses your local keys instead of keys installed on the server.
ssh_options[:forward_agent] = true
ssh_options[:keys] = %w('~/.ssh/id_rsa.pub')

# shared hosts e.g. hostgator prevent filfefs with high (>5) group privileges from being run (rightfully)
set :group_writable, false

# You will probably have to update any submodules that are have an SSH remote to use https e.g.
# git@github.com/Wordpress/Wordpress.git
# to 
# https://github.com/WordPress/WordPress.git